The present invention is directed to the fields of power converters, inverters, electric vehicle charging equipment, and related fields.
Due to the rising popularity of electric vehicles (EVs) on the market today, demand for high power electrical grid connections has greatly increased due to a need for high power EV charging stations. Desirable charging rates of high capacity electric vehicle batteries require high power levels that are not available from typical household electrical systems. As such, electrical connections that can provide high voltage AC or DC “Level 2” or “Level 3” Electric Vehicle Service Equipment (EVSE) are important to the growth of the electric vehicle service industry.
In some cases, an EVSE may rely on batteries to provide the energy needed for EV charging. This is especially useful in applications where the EV is charged by a mobile or portable energy storage device or in applications where use of the EVSE would lead to excessive utility demand charges. However, problems may arise when sourcing safety-certified charging equipment to work with these batteries and other energy storage devices, as most inexpensive commercially-available EVSEs require high voltage three-phase AC power to run from. Energy storage devices such as lithium-ion batteries do not innately provide this power form and thus require that EVSE be connected to the energy storage devices through DC-to-AC power converters that bring the voltage output of the energy storage devices to a form suitable for the EVSE to charge a vehicle. Acquiring or building power converters for these energy storage devices that can perform these tasks safely and reliably is expensive and time consuming for many reasons, not the least of which is the need to obtain regulatory safety approval from organizations such as Underwriters Laboratories (UL). Powering an EVSE that requires three-phase 240-volt AC input is especially difficult because of the prohibitive cost of obtaining three-phase inverters on the market today and the prohibitive expenditure of time needed to gain safety approval from UL and other related entities.